1. Field of the Invention
The present invention relates to a working apparatus which applies machining or working against, for example, industrial parts having a common character (hereinafter referred to as "work piece") worked by machine tool, or against any other work pieces manufactured by die-cast injection molding, punching press, lost wax casting, closed die forging, etc., so as to chamfer according to the contour, or to finish the outer peripheral end surface to be a prescribed accuracy of working. More particularly, the present invention relates to a working apparatus which may apply a desired machining or working to the work piece without requiring complicated control or structure.
2. Description of the Related Art
FIG. 20 shows an example of work piece manufactured through machining or working by machine tool, die-cast injection molding, punching press, lost wax casting, closed die forging, etc. A work piece 201 in FIG. 20 has somewhat a complicated two-dimensional shape because of combination or linear lines and curved lines. The work piece 201 has a flange-shaped form, in which a penetration hole 203 is formed through which an unillustrated shaft penetrates. The work piece 201 also has other penetration holes 205 at the four corners thereof in which unillustrated clamp screws are inserted. In addition, a ring depression 207 is formed around the outer periphery of the penetration hole 203, and the ring depression 207 has a plurality of protrusions 209. The thus described structure of the work piece 201 is engaged with or fixed on other unillustrated work pieces to be finished as a predetermined device.
In regard to the work piece 201 as shown in FIG. 20, although the accuracy of dimension is severely required as for pitches P1 or P2 between the penetration holes 205 and 205, it is rather unimportant to obtain an absolute accuracy as for the contour thereof.
It is necessary to remove rough part on edges of the outer periphery resulting from manufacturing process, namely burr. It is also necessary to chamfer according to the contour or to finish the end surface to be a prescribed accuracy of working. At that time, if a mere removal of burr is to be made, it is sufficient to use flexible tools such as brushing wheel or wire wheel. However, if the chamfering according to the contour, or the finishing of the end surface, should be carried out under a prescribed accuracy of working, it is necessary to use any cutting tool such as end mill, rotary bar, chamfer cutter, etc.
FIGS. 21 and 22 show examples of cutting apparatuses for finishing by using the above cutting tools. There is a base 301, on which an index table apparatus 303 is mounted. A work piece 305 as an object to be cut is placed on this index table apparatus 303, and is clamped by a air-cylinder type of clamp unit 307 provided above the work piece 305.
There is a slide table 309 provided on the base 301, and the slide table 309 forwardly and rearwardly moves in the direction of the work piece 305 by an air cylinder 311. As illustrated in FIG. 22, there is a coil spring 313 attached on the base end of the slide table 309. The slide table 309 also has a cutter driving unit 315 at the top thereof, and a rotary bar 317 is attached on the top of the cutter driving unit 315. The rotary bar 317 performs cutting by being pressed onto the outer periphery of the rotating work piece 305.
For reference, a predetermined pressing force is applied to the rotary bar 317 during being pressed onto the work piece 305 by means of the coil spring 313.
The index table apparatus 303 has a work piece-shaped model cam 319 mounted on the bottom thereof, and there is also a stylus roller 323 mounted on the side of the slide table 309 via an arm 321. When the index table apparatus 303 rotates, the work piece-shaped model cam 319 also rotates, thereby the slide table 309 forwardly and rearwardly moves along the contour of the work piece-shaped model cam 319 via the stylus roller 323. In such a structure, the positioning of the rotary bar 317 against the work piece 305 is controlled, thus the work piece 305 is cut according to the contour of the work piece-shaped model cam 319.
For further explanation, reference numeral 331 is a control board, and 333 is a chamfering amount adjusting knob.
There is another example of cutting apparatus as illustrated in FIGS. 23 and 24. There is a base 401, on which an X/Y servo slide unit 403 is mounted. As illustrated in FIG. 24, the X/Y servo slide unit 403 comprises an X-axis slider 405 and a Y-axis slider 407, and the Y-axis slider 407 is provided with a cutter driving unit 408. The cutter driving unit 408 has an end mill 409 at the top thereof.
The Y-axis slider 407 moves in the X-axial direction by means of the X-axis slider 405, and the cutter driving unit 408 moves in the Y-axial direction by means of the Y-axis slider 407. Therefore the cutter driving unit 408 may move both in the X and Y directions so as to move to an arbitrary coordinate (X/Y) position.
The base 401 is further provided, for example a three-claw type of air chuck 411 thereon, and a work piece 413 is placed and fixed on this three-claw type of air chuck 411. Further, a control board 415 and a servo slide unit controller 417 are provided in the upper section above the base 401. In addition, as illustrated in FIG. 24, a cutting oil nozzle 419 and an air blowing nozzle 421 are provided in the cutting apparatus which uses the end mill 409, to which cutting oil and compressed air are respectively supplied. There are also various switches 423 such as an actuation switch or an emergency stop switch in the lower section above the base 401.
For further explanation, reference numeral 425 in FIG. 24 is a stopper for positioning of the work piece 413.
In the thus described structure, the work piece 413 is held at the predetermined position by the three-claw type of air chuck 411. In addition, the tracking information of the end mill 409 has already been input and stored in a servo slide unit controller 417 via an unillustrated teaching box, etc. The tracking information is used for finish the work piece 413 according to a predetermined dimension and shape. Thus the control signal from the servo slide unit controller 417 actuates the X/Y servo slide unit 403, so that the end mill 409 may carry out the movement according to the predetermined track information, thereby a predetermined cutting is performed against the work piece 413.
However, the prior arts as above described have the following problems.
With regard to the work piece 201 illustrated in FIG. 20, as already discussed, the absolute accuracy of dimension of contour is not so important, and in fact there is a deviation of contours of the manufactured work pieces. For a large number of work pieces 201 having deviation of contours, it is necessary to remove the burr and to chamfer according to the contour, or to finish the end surface to be a prescribed accuracy of working.
When considering the prior arts of cutting apparatus from this point of view, every apparatus has a structure to carry out the uniform cutting against any of the work pieces 305 or 413 according to the work piece-shaped model cam 319 or to the tracking information set in advance based on the model work piece. Therefore, when there is a deviation of contour of the work piece 305 or 413, the depth of cutting may also deviate, which results in excessive amount or size of chamfering due to excessive depth of cutting at several positions, and in some case, results in damage to the tool. In addition, there may also be a case that the sufficient depth of cutting is not obtained to result in small amount or size of chamfering, which in the extreme condition causes the burr to partially remain without being removed. As above described, according to the prior arts relating to the cutting apparatus, there has been a problem that the deviation of the finished condition may occur due to deviation of contours of the work pieces.
Further, there is another problem of the difficult operation, especially for the cutting apparatus as shown in FIGS. 23 and 24. In regard to the cutting apparatus in FIGS. 23 and 24, as above described, it is necessary to input and store the tracking information in advance corresponding to the shape of the work piece. However, the input and store procedures should be done in practice by setting many programming points along the contour in order to determine the X/Y coordinates of these programming points, and the obtained programming points are then input and stored by using the teaching box. This kind of input and store procedures is not an easy operation at all, and whenever the type of work piece changes, the corresponding change of programming points is required. In addition, when the contour of work piece becomes more complicated, the number of programming points should be increased, which will require more difficult operation.
From this point of view, the applicant of the present invention has already invented "a following working apparatus" of which details are disclosed in Unexamined Japanese Patent Publication No. Hei 5-200655.
However, according to the "following working apparatus" as disclosed in Unexamined Japanese Patent Publication No. Hei 5-200655, the pressing force, which is applied to a working apparatus to pressingly be in contact with a work piece, is detected by a load sensor. Although such a structure of the "following working apparatus" has been simplified in total and hence a remarkable facile operation has been accomplished, the structure thereof is still complicated and expensive due to the control based on the detected amount by load sensor, or to the program control by servo motor.